STUDIES ON POPULATION DENSITY OF DIFFERENT BIOINOCULANTS IN TURMERIC PLANTATION SOILS FOR BIOCONTROL ACTIVITY

Abstract

Turmeric (Curcuma longa L) is an herbaceous annual plant belonging to the family Zingiberaceae in which curcumin has been identified as the active principle compound. The quality of turmeric rhizomes is being affected by various pests and diseases which in turn reduce the quality of rhizomes. Turmeric is an important exportable spice for India. In most of the foreign countries, turmeric price is fixed based on the appearance of rhizomes and curcumin content. In order to get the maximum yield in turmeric, planters used to apply a variety of inorganic chemical fertilizers and agrochemicals for controlling pests and diseases. Furthermore, constant and indiscriminate applications of agrochemicals and mineral fertilizers pollute the environment and soil and also hazardous to animal and human health. Organic farming is a crop production method which encourages sustainable agriculture by enhancing the biological cycles in nature. The present study envisages studying the population density of different known bioinoculants strains in turmeric rhizosphere soil samples. The antagonistic activity of Bioinoculants was studied by performing test against rhizome rot pathogen, Pythium aphanidermatum. Plant growth promoting rhizobacteria (Bioinoculants ) have been proved as efficient biocontrol agents in controlling various plant diseases besides, enhancing the plant growth significantly. The results revealed that Bioinoculants such as Bacillus, Pseudomonas, Trichoderma and Streptomyces spp. were identified and present predominantly in the soils of turmeric plantations. The population diversity was further correlated with the soil nutrient status. The microbial population of Bioinoculants and soil nutrient contents were carried out both in the rhizosphere and non-rhizosphere soils. The results indicated that the microbial population was found to be more in rhizosphere than in non-rhizosphere soils and there was a positive correlation between microbial population and soil nutrient contents.